Berserk's ending were fairly interresting, cant remember when i had that feeling last.
In retrospect i remeber that my reaction were like "NOOOO!! WTF!!? it CANT end like THAT!!".
After thinking about it i realized it were one of the better and more unexpected endings ive seen.
as I understand Berserk anime did not have ending...well I guess you was refering to manga
I don't know why but I could never bring myself to watch the whole Berserk, I always whatched the first part and after that forgot about it, done it quite a few times. I know that it is supposed to be good anime, and as far as I saw it it was, but eh, should watch that thing finally >_<
as for the endings:
Unexpected ending is what I like, otherwise it's boring.
Everybody goes insane!!!
Texhnolyze has a destructive ending...
this what I like in endings

The best ending I can remember, the ending that made most impact on me, as I still remember it after only seeing it once is ending of Serial Experiment Lain. Thou it was kind of good and kind of happy ending, but there was not quite happy Lain and her sister that was the only one left out after all the time/event changing and so on. It was sad. "happy", destructive, reconstructive and someone was insane. What can be better?

(think I should watch that anime again)
Hmm, I can remember any good unexpected ending right now, there was this one 25-27 ep anime about space and two brothers fighting all the time and killing each other at some point and then the bad one turned good only in last ep...the ending was super sweet and so on, but I was thinking that the good one will stay and survive not the bad one, as he was bad to the core. Oh well not really something unusuall, but it was quite unexpected for me. and I think there was some insane person dying also involved. Oh, the bad brother help to drowe her trofy wife into insanity and she died, or something like that. Dar cant remember the title of the anime.....